1. Field of the Invention
The present invention relates to modified clay minerals. The present invention further relates to emulsion compositions which contain such a modified clay mineral.
2. Discussion of the Background
Emulsion compositions include W/O type (water-in-oil type) compositions and O/W type (oil-in-water type) compositions. Generally, W/O emulsion compositions have poor emulsion stability as compared to O/W emulsion compositions and tend to permit easy separation of an oil solution from water, particularly when they have low viscosity. Thus, there have been attempts to enhance the emulsion stability (temperature stability) of W/O emulsion compositions.
Japanese Patent Application Publication No. JP-A-61-129033 proposes a method of stabilizing a water-in-oil emulsion composition by the use of, as an emulsifying aid, an organic modified clay mineral obtained by treating a water swellable clay mineral with a quaternized ammonium salt type cationic surfactant and a non-ionic surfactant. Although an apparent stabilizing effect is obtained, the composition causes skin irritation when used as an emulsion composition, since the quaternized ammonium salt type cationic surfactant used for treating the organic modified clay mineral remains. In addition, the composition is not entirely satisfactory from the aspect of moisture retention property.
Accordingly, there is a high demand for a material that provides an emulsion stabilizing effect on an emulsion composition, inter alia, a W/O emulsion composition, hardly causes skin irritation, and provides a moisture retention property.